Census Year 1990 Tract Polygons. This dataset contains polygon features, created as part of the DC Geographic Information System (DC GIS) for the D.C. Office of the Chief Technology Officer (OCTO) and participating D.C. government agencies. 2000 census tracts are identical to 1990 census tracts, except in instances where multiple tracts were merged to form one new tract. Census tracts were identified from maps provided by the U.S. Census Bureau and the D.C. Office of Planning. The tract lines were created by selecting street arcs from the WGIS planimetric street centerlines, and, where necessary, heads-up digitized from the 1995/1999 orthophotographs. Polygons were generated using these lines.